Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted. 相似文献
AIM: To investigate a possible interaction between lolitrem B and ergovaline by comparing the incidence and severity of ryegrass staggers in sheep grazing ryegrass (Lolium perenne) containing lolitrem B or ryegrass containing both lolitrem B and ergovaline.
METHODS: Ninety lambs, aged approximately 6 months, were grazed on plots of perennial ryegrass infected with either AR98 endophyte (containing lolitrem B), standard endophyte (containing lolitrem B and ergovaline) or no endophyte, for up to 42 days from 2 February 2010. Ten lambs were grazed on three replicate plots per cultivar. Herbage samples were collected for alkaloid analysis and lambs were scored for ryegrass staggers (scores from 0–5) weekly during the study. Any animal which was scored ≥4 was removed from the study.
RESULTS: Concentrations of lolitrem B did not differ between AR98 and standard endophyte-infected pastures during the study period (p=0.26), and ergovaline was present only in standard endophyte pastures. Ryegrass staggers was observed in sheep grazing both the AR98 and standard endophyte plots, with median scores increasing in the third week of the study. Prior to the end of the 42-day grazing period, 22 and 17 animals were removed from the standard endophyte and AR98 plots, respectively, because their staggers scores were ≥4. The cumulative probability of lambs having scores ≥4 did not differ between animals grazing the two pasture types (p=0.41).
CONCLUSIONS AND CLINICAL RELEVANCE: There was no evidence for ergovaline increasing the severity of ryegrass staggers induced by lolitrem B. In situations where the severity of ryegrass staggers appears to be greater than that predicted on the basis of concentrations of lolitrem B, the presence of other tremorgenic alkaloids should be investigated. 相似文献
DNA barcoding has been proposed as a method for species identification. However, this method has been criticised for its over-reliance on a single mitochondrial gene. In this study, four mitochondrial gene regions and one nuclear gene region were used to investigate their different abilities to identify tissue associated with museum specimens of Aethomys chrysophilus, Aethomys ineptus and Micaelamys namaquensis. Aethomys chrysophilus and the more recently elevated A. ineptus are indistinguishable on morphological grounds; however, their ranges are largely parapatric with only one syntopic locality currently known. All of the mitochondrial gene regions were able to separate M. namaquensis from A. chrysophilus and A. ineptus, but they varied in their abilities to resolve differences between A. chrysophilus and A. ineptus. The sequence results identified a specimen from KwaZulu-Natal that was misclassified and should have been identified as A. ineptus. Seven specimens that had not been reclassified following the elevation of A. ineptus to species level were identified as A. ineptus. Individuals of A. chrysophilus from Malawi could not be classified as either A. chrysophilus or A. ineptus, and may be a hybrid or a new, distinct species. This study indicates that DNA barcoding may be used to separate M. namaquensis from A. chrysophilus and A. ineptus, and although it was not able to separate A. chrysophilus and A. ineptus, it did indicate specimens from Malawi may be a new cryptic species. 相似文献
This study evaluated the application of stable isotopes of carbon as an alternative and more accurate method to determine gastrointestinal transit time (GTT) in fish by comparing it to the inert marker method. The stable isotope method detects alterations of the normal carbon flow in a biological system by analyzing naturally occurring isotopes of carbon, contrary to studies based on conventional techniques that apply external markers to the diet to determine GTT through visual observation of the color change in feces. Therefore, 320 pacu, Piaractus mesopotamicus juveniles were reared in 32 tanks under two different temperatures (25 and 29 C). The pacu juveniles received two different diets, one based on ingredients derived from C3 photosynthetic cycle plants and the other based on C4 plant ingredients, both containing titanium oxide (TiO2) as a marker. After 40 d, the isotopic signature of the diets was changed, and the marker was replaced by chromic oxide (Cr2O3). In the isotopic technique, the feces were analyzed to determine the exchange in the isotopic ratio of carbon δ13C. Both methods found that GTT was faster (nearly 6 h) in fish at 29 C when using the C4/C3 feeding strategy and slower in fish at 25 C using the C3/C4 strategy (15 h by inert marker and 18 h by the isotopic method). In conclusion, GTT determination in pacu juveniles using the stable isotope technique exhibits the same accuracy obtained with the inert marker method at temperatures suitable (nearly 29 C) for the metabolism of these animals. 相似文献
A technique is described for the visual examination and biopsy sampling of the affected organ in canine liver and pancreatic dysfunction. Résumé . On a décrit une technique pour l'examen visuel et la biopsie d'essais de l'organe affecté dans le foie du chien et le mauvais fonctionnement du pancreas. Zusammenfassung . Man hat eine Technik beschrieben, für die Sichtprobe und die Biopsie-Probenahme des angegriffenen Organs in der Hundeleber und in der Bauchspeichelschlechtfunktion. 相似文献
Items for inclusion in this section should be sent at least 6 weeks prior to publication date, which is approximately 18-20th of each month, to the Editor, Journal of Small Animal Practice, 142 North Road, Hertford, Herts., England. 相似文献
Thirty nonlactating Holstein cows were superovulated to determine the effect of artificial insemination time on fertilization status and embryo quality. During the luteal phase of the estrous cycle, cows were administered 38 mg FSH-P in a 4-d descending dose regimen. Luteolysis was induced with two injections of prostaglandin on the last day of FSH-P treatment. All cows were continuously monitored for behavioral estrus using the HeatWatch estrus detection system. All cows were inseminated once with one .5-mL straw (50 x 10(6) sperm) at either 0 (n = 10), 12 (n = 10), or 24 h (n = 10) after the first standing event. The elapsed time (mean +/- SD) from the first prostaglandin dose to the first standing event was 39.4 h +/- 7.7 h. The (mean +/- SD) duration of behavioral estrus was 13.2 h +/- 4.1 h. The (mean +/- SD) number of standing events was 27 +/- 17. Five hundred twenty-nine embryos and ova were recovered nonsurgically 6 d after insemination. Fertilization rates were 29 (0 h), 60 (12 h), and 81% (24 h) (P < .01). Percentages of excellent and good, fair and poor, and degenerate embryos were not different (P > .05). Percentages of embryos with accessory sperm were 5 (0 h), 8 (12 h), and 41 (24 h) and differed between the 0 and 24 h and the 12 and 24 h inseminations (P < .01). Artificial insemination of superovulated, nonlactating Holstein cattle 24 h after onset of estrus increased fertilization rate and percentage of embryos with accessory sperm compared with insemination at 0 or 12 h after onset of estrus. Embryo quality was not affected by time of insemination. 相似文献